Mulch is helpful for gardeners to keep weeds under control and maintain moisture in the garden. However, it's not helpful for dogs. Cocoa mulch contains theobromine, which is toxic for dogs, and like other mulches, presents choking and intestinal hazards. If you want to mulch your garden, use a less hazardous material or keep your dog away from mulched areas.
Cocoa Mulch Dangers
Cocoa mulch is popular because it emits a delicious chocolate aroma and holds up well in the garden with time. However, that cocoa smell can lead to trouble for a dog. Many dogs have a natural affinity for chocolate and the temptation of cocoa mulch may be more than even the best dog can handle. If a dog thinks your cocoa mulch has snacking potential, he runs the risk of theobromine poisoning. Cocoa mulch is comprised of discarded cocoa bean shells or hulls. Theobromine still resides in the hulls, and if ingested, may cause vomiting, diarrhea, anxiety, panting, racing heart rate, hyperactivity, tremors, dark red gums and seizures.
Cocoa mulch isn't the only choice for the garden; there are a variety of colorful landscaping mulches on the market. According to the University of Massachusetts Amherst, the dyes coloring the mulch aren't a great a concern -- there's no evidence they are toxic -- but the type of wood used for colored mulch may contain toxic chemicals. Such mulches often comprise recycled wood, such as wood pallets and reclaimed wood from demolition and construction sites, potentially contaminated with a variety of chemicals such as creosote and chromated copper arsenate. Arsenic-based wood preservatives have been banned for residential products since 2003, however, the wood is still abundant in fences and older decks, available for mulching. If you elect to use colored mulch as a substitute for cocoa mulch, try to learn the wood's source.
Other Mulch Dangers
Dr. Justine Lee of the Pet Health Network notes that most mulches are safe for dogs, not causing a toxic reaction. However, a dog eating mulch still runs the risk of ingesting foreign bodies, presenting choking hazards as well as esophageal inflammation, scarring and perforation. Ingesting pieces of mulch may perforate his intestines and cause an intestinal obstruction.
If your dog is a chewer, it's probably best to avoid mulch altogether. Using a non-toxic mulch still presents the potential problem of chewing and ingesting the large bits of bark and wood. Consider using shredded pine, buckwheat hulls or hay as mulching material or block your dog's access to mulched beds.
You can control your home gardening choices, however your dog may still encounter dangerous mulch when you're visiting the park or friends. Keep your dog on leash and stay alert to minimize the chance he'll snag some mulch. If he exhibits symptoms of theobromine poisoning, he should see a vet.